PLoS ONE (Jan 2015)

Mortality amongst patients with influenza-associated severe acute respiratory illness, South Africa, 2009-2013.

  • Cheryl Cohen,
  • Jocelyn Moyes,
  • Stefano Tempia,
  • Michelle Groome,
  • Sibongile Walaza,
  • Marthi Pretorius,
  • Halima Dawood,
  • Meera Chhagan,
  • Summaya Haffejee,
  • Ebrahim Variava,
  • Kathleen Kahn,
  • Anne von Gottberg,
  • Nicole Wolter,
  • Adam L Cohen,
  • Babatyi Malope-Kgokong,
  • Marietjie Venter,
  • Shabir A Madhi

DOI
https://doi.org/10.1371/journal.pone.0118884
Journal volume & issue
Vol. 10, no. 3
p. e0118884

Abstract

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Data on the burden and risk groups for influenza-associated mortality from Africa are limited. We aimed to estimate the incidence and risk-factors for in-hospital influenza-associated severe acute respiratory illness (SARI) deaths.Hospitalised patients with SARI were enrolled prospectively in four provinces of South Africa from 2009-2013. Using polymerase chain reaction, respiratory samples were tested for ten respiratory viruses and blood for pneumococcal DNA. The incidence of influenza-associated SARI deaths was estimated at one urban hospital with a defined catchment population.We enrolled 1376 patients with influenza-associated SARI and 3% (41 of 1358 with available outcome data) died. In patients with available HIV-status, the case-fatality proportion (CFP) was higher in HIV-infected (5%, 22/419) than HIV-uninfected individuals (2%, 13/620; p = 0.006). CFPs varied by age group, and generally increased with increasing age amongst individuals >5 years (p<0.001). On multivariable analysis, factors associated with death were age-group 45-64 years (odds ratio (OR) 4.0, 95% confidence interval (CI) 1.01-16.3) and ≥65 years (OR 6.5, 95%CI 1.2-34.3) compared to 1-4 year age-group who had the lowest CFP, HIV-infection (OR 2.9, 95%CI 1.1-7.8), underlying medical conditions other than HIV (OR 2.9, 95%CI 1.2-7.3) and pneumococcal co-infection (OR 4.1, 95%CI 1.5-11.2). The estimated incidence of influenza-associated SARI deaths per 100,000 population was highest in children <1 year (20.1, 95%CI 12.1-31.3) and adults aged 45-64 years (10.4, 95%CI 8.4-12.9). Adjusting for age, the rate of death was 20-fold (95%CI 15.0-27.8) higher in HIV-infected individuals than HIV-uninfected individuals.Influenza causes substantial mortality in urban South Africa, particularly in infants aged <1 year and HIV-infected individuals. More widespread access to antiretroviral treatment and influenza vaccination may reduce this burden.